In a large mixing bowl, cream butter and sugar for 4-5 minutes until light and fluffy. Scrape the sides of the bowl and add the eggs and vanilla. Cream for 1-2 minutes longer.
Stir in flour, cream of tartar, baking soda, and salt, just until combined.
In a small bowl, stir together sugar and cinnamon.
If time allows, wrap the dough and let refrigerate for 20-30 minutes.
Roll into small balls until round and smooth. Drop into the cinnamon-sugar mixture and coat well.
Place on a parchment paper-lined baking sheet (these cookies spread out a lot, so leave at least an inch surrounding each). Bake for 9-11 minutes (usually closer to 11). Let cool for several minutes on baking sheet before removing from the pan.
